Estimating the Absorbed Dose of Organs in Pediatric Imaging of ۹۹mTc-DTPA Radiopharmaceutical using MIRDOSE Software

Introduction: In this study, organ radiation doses were calculated for the renal agent ۹۹mTc-DTPA in children. Bio-kinetic energy of ۹۹mTc-DTPA was evaluated by scintigraphy and estimates for absorbed radiation dose were provided using standard medical internal radiation dosimetry (MIRD) techniques.Material and Methods: In this applied research, fourteen children patients (۶ males and ۸ females) were imaged using a series of planar and SPECT images after injecting with technetium-۹۹m diethylenetriaminepentaacetic acid (۹۹mTc-DTPA). A hybrid planar/SPECT method was used to plot time-activity curves to obtain the residence time of the source organs and also MIRDOSE software was used to calculate the absorbed dose of every organ. P-values were calculated using t-tests in order to make a comparison between the adsorbed doses of male and female groups..Results: Mean absorbed doses (µGy/MBq) for urinary bladder wall, kidneys, gonads, liver and adrenals were ۲۱۳.۵±۴۷.۸, ۱۲.۹۷±۶.۲۳, ۱۲.۰±۲.۵, ۴.۲۹±۱.۴۷, and ۳.۳۱±۰.۹۶, respectively. Furthermore, the mean effective dose was ۱۷.۵±۳.۷ µSv/MBq. There was not any significant difference in the mean absorbed dose of the two groups.Conclusion: Bladder cumulated activity was the most contribution in the effective dose of patients scanned with ۹۹mTc-DTPA. Using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest. Moreover, patient-specified internal dosimetry is recommended.

Keywords:

Internal Dosimetry , Hybrid Planar/SPECT Method , MIRDOSE Software , ۹۹mTc-DTPA